Dry kiln



Oct. 19, 1937. J w, DOHERTY 2,096,373

DRY KILN Filed May 25, 193s 2 sheets-sheet 1 To ELec-rmc wrzig/c1 Oct. 19, 1937. J. w. DoHERTY 2,096,373

DRY KILN Filed May 23, 1936 2 Sheets-Sheet 2 Patented Oct. 19, 1937 PATENT 4OFFICE DRY KILN James W. Doherty, Hyde Park, Mass., assigner to B. F. Sturtevant Company, Hyde Park, Boston,

Mass'.

Application May 23, 1936, Serial No. 81,451

6 Claims.

This invention relates to drying systems and relates more particularly to the drying of lumberand'the like, in what are known as dry kilns.

In kilns for the drying of lumber in the form 5 ofboards'orplanks, it iscustomary to so stack the boardsv in the kiln, that interstices between the boards are formedand through which, heated air is blown under forced draft to dry out both r'sidesv of the lumber.

It has been appreciated that the heated air as it passes through the stacked lumber, loses through its absorption of moisture and loss of heat, its elfectiveness to a considerable degree, so it has-been customary to provide reversible fans for causing the drying air stream to enter rstone side of the stack'to be dried, and then after a period of time, the opposite side. It has however, been the practice in the past to'mount the reversible fans*` in openings in transverse walls, so that the columns of drying air initiated kby, vthe, fans'are rst projected longitudinally of the kiln.r The columns of air are then deflected crosswise the kiln byzigzag walls orbales Ito perform'their drying duty. This arrangement however, not only isA ineicient in thatconsiderable energy is wasted in turning the columns of air rat right angles to their original'courses, but the drying chamber is necessarily complicated by 4the multiplicity of deilecting walls required, andr finally Whatis even more serious, the lumber'is unevenly dried due to vthe 'tendency of the columns of air to drift, after turning, towards that end of the kiln towards which they were originally projected. n

yAccording to this invention, there is provided in the drying or fan chamber of a dry kiln, a single central longitudinal wall provided with a plurality of spaced openings in which reversible disc type kfans are mounted. The fans are all rotated from a single reversible motor, by means of a longitudinal shaft common to all fans, and ay set of gears, anda transverse shaft for each fan.

An object of the invention is to provide a simple, efficient fan system for dry rkilns of the internal fan type.

Another object of the invention is to provide a Y fan system for dry kilns of the internal fan type, in which the drying air is projected crosswise the kiln, without longitudinal drift.

Otherobjects of the invention will be apparent from the following description taken together with the drawings.` The invention will now be described with reference to the drawings of which: i

Fig. 1 is a plan view looking downwardly, with portions of the upper and lower kiln chamber in section, of an internal fan kiln according to this invention; y

Fig. 2 is a detail view of the gear drive for each of the fans of Fig. l;

Fig. 3 is a longitudinal section through one end of the kiln of Fig. 1;

Fig. 4 is a partial side view in section of the kiln of Fig. 1, and y Fig. 5 is an end View in section of the kiln of Figs. 1 and 3.

With reference t'o Figs. 3 and 4, the lumber to be dried is stacked in the drying chamber 6 upon the` oor member 1, which in turn is mounted upon the wheels 8 which rest upon the track rails 9. The successive layers of lumber I are spaced apart in the usual manner-to form a plurality of horizontal channels therebetween, through which the drying air is forced.

VThe fresh air inlets II contain the dampers IIA and the exhaust air vents I2 contain the dampers I2A. Fresh air is drawn in through one or the other of the two series of inlets II, depending upon the direction of rotation of the fan. One of the dampers IIA of Fig. 4 is closed and the other open when the fan is rotating in one direction, and when the fan is rotating in the other direction, the positions of these dampers are reversed. The exhaust air always passes out through the center vents I2.

Underneath the drying chamber 6 is the fan chamber I3, down the longitudinal center of which extends the wall I4 provided with the spaced circular openings I in which are mounted the fans I6. The fans I6 are rotated from the longitudinal shaft I'I which is driven by the motor I8 in the apparatus room I9 by means of the V-drive 20. Each fan I6 is driven as shown by Fig. 2, from the shaft I1 by the gear 3 which is keyed to the shaft II and which is meshed with the gear 32 which is keyed to the shaft of the fan.

, The motor I8 is provided with a standard type of reverser 22 forlchanging the polarity of the current supplied from the electric main to windings of the motor I8.

The wall I 4 divides the fan chamber into two parts in each of which are arranged the longitudinal steam heating coils 23 for heating the drying air.

In operation the fans I6 may first be rotated as shown by the arrows in Fig. 4 to draw fresh air in through the right hand inlets II (facing the drawings) and to project the drying air through the fan chamber I3 from right to left and through the lumber in the drying chamber from left to right. After a period of time which experience has shown to be correct, the fanrdriv# Y ing motor I8 is reversed so that the fans I6 rotate in the opposite direction to reverse the previously described air flow. At the same time, the dampers IIA in the right hand inlets II are closed and the dampersl IA in theleft Vhand irr-A lets are opened. y l

Regardless of the directionY of rotation ofthe fans I6, the exhaust air is vented out the cen-l s trally placed vents I2. Thus, the exhaust air is always made up of moist air which has previously A- performed the function of admitting fresh air and venting exhaust air. v Y

As may be readily appreciated from Fig. 1 the air projected by the fans I6 passes in directilow transversely the kiln without driftu to one or the other ends of the kiln as has been the practice in the past. This ensures that every portion of the lumber is dried an equal amount regard-` less of whether it is located adjacent or between the two ends of the kiln. j

The fans are all driven from a single motor which is not exposed to-and is therefore not affected by the drying atmosphere. TheY shaft I'I and gears 3| and 32 are not affected by the drying atmosphere and provide a simple dependable driving mechanism.

While one embodiment of the invention has been disclosed for the purpose of illustration, it should be understood that the invention is not limited to the exact arrangement described, since many departures would suggest themselves to those skilled in the art, afteraccess to this disclosure. 1

What is claimed is:

1. A dry kiln comprising a drying chamber, means for supporting material tobe dried in said drying chamber in two separate stacks with a central space therebetweenand with side spaces between the longitudinalV sides of said drying chamber and said stacks., means forming fresh air inlets over said side spaces, meansforming exhaust air vents-over said central space, a fan chamber under said drying chamber, a wall extending down the longitudinal center of said fan chamber and dividing same into two compartments, -each of said compartments connecting with one of said side spaces, said wall having a plurality of openings, fans vin said openings, means mounted external said fan and drying chamber for rotating said fans, and means for reversing said last mentioned means.

.2; A .dry kiln comprising a drying chamber, means for supporting material to be dried in said chamber in two separate stacks with a central space therebetween and with side spaces between the longitudinal sides of said chamber and said stacks, said stacksincluding a'plurality of horizontal air channels, means forming fresh air inlets opening into said side spaces, means forming exhaust air vents over said central space, a fan chamber under said drying chamber and communicating directly with said side spaces, and an air tight partition between said central space and said fan chamber, whereby air from said fan chamber can only reach said central space through said side spaces and through said channels.

3. A dry kiln comprising a drying chamber, means for supporting material to be .dried in said chamber in two separate stacks with aV central space therebetween and with side spaces between the longitudinal sides of said chamber and said stacks, said stacks including a plurality of horizontal air channels, means forming fresh air inlets opening into said side spaces, means form- Y ing exhaust air vents over said central space, a fanhamberyunder Said `drying Chamber and communicatingldirectlywith said side spaces, an air tight partition between said central space and said fan chamber, whereby air from said fan chamber can only reach said central space Y through said side spaces and through said channels, and reversible means for alternately drawing air from said drying chamber through one of said side spaces acting as a recirculated air passage, into said fan chamber and forcing air from said fan chamber through the other of said side spaces acting as an air discharge passage, into said drying chamber.

f 4. A dry kiln'comprising a vdrying chamber,

means for supporting material lto be dried inl said chamber intwo separate stacks with a cen` tral `space therebetween and withv side spaces between the longitudinal sides of said chamber and said stacks, said stacks including a plurality of horizontal air channels, means forming fresh air inlets opening into said side spaces, means forming exhaust air vents over said central space, a fan Y chamber under said drying chamber and communicating directly with said side spaces, an air tight partition between said central space andsaid fan chamber, whereby air from said fan chamber can only reach said central space through said side spaces and through said channels, and reversible means for alternately drawing air from said drying chamber through one of said side spaces acting as a recirculated air passage, into said fan chamber and forcing air from said fanv chamber through the other of said side spaces acting as an air discharge passage, into said drying chamber, the fresh air inlets for the one ofsaid side spaces acting asa Vrecirculated air. passage being opened and the fresh air inlets for Hthe one of said side spaces acting as a discharge lair passagebeing closed. Y

5. A dry kiln comprising a drying chamber, means for supporting material to be dried in said chamber in two separatestacks with a central f through said side spaces and through said chan- Y nels, a wall extending down the longitudinal center of said fan chamber and dividing same into two-compartments, each of said Acompartments connecting directly with one of said vside spaces, said wall having a plurality of openings, fans in said openings, means external said drying chamber for rotating said fans, and means for reversing said last mentioned means.

6. A dry kiln comprising Ya drying chamber, means for supporting material to be dried in said chamber in two separate stacks with a central space therebetween and with side spaces between the longitudinal sides of said chamber and said stacks, said stacks including a plurality of horizontal air channels, means forming fresh air inlets opening into said side spaces, means forming exhaust air vents over said central space, a fan chamber under said drying chamber and communicating directly with said side spaces, an air tight partition between said central space and said fan chamber, whereby air Vfrom said fan chamber can only reach said central space through said side spaces and through said channels, a wall extending Vdown the longitudinal center of said ian chamber and dividing same into two compartments, each of said compartments connecting directly with one of said side spaces, said wall having a plurality of openings, fans in said openings, means external said drying chamber for rotating said fans, and means for reversing said last mentioned means, said fans when rotating in one direction draw air from said drying chamber through one of said side spaces acting as a recirculated air passage, into said fan chamber and force air from said fan chamber through the other of said side spaces acting as an air discharge passage, into said drying chamber, the fresh air inlets for the one of said side spaces acting as a recirculated air passage being opened and the fresh air inlets for the one of said side spaces acting as a discharge air passage being closed. JAMES W. DOI-IERTY. 

